Mr Clark your partially correct, the outer skin is for wear resistance, once you go thru the skin the inner core is much softer than modern steel. The point I was trying to make I have two 1909 Argentine mausers one has been rebarrel to a 280REm the other 338/06, the 280Rem is fine the 338/06 isn't. The serial # Prefix for my 338/06 is A, which means my rifle was in the first lot delivered, I also believe there could have been a problem with the heat treatment. While I can't be positive I think my son's rifle Prefix was a B placing it in the second lot delivered. In therory all the 1909 Argentine rifles received the same heat treating etc etc, I read or heard some of these rifles failed there proof tests. Non the less the Mauser actions are superb but I don't think they should be hot rodded, I would recommend that the loading for the custom mauser not exceed the pressure levels of the original 257 Roberts pressure level. If GDCPony adheres to the original loading he's not going to get in any trouble. Type this in under search ( Argentine 1909 mauser) Looks like this was covered before.... William